1. Field of the Invention
The present invention pertains to respiratory masks, and more specifically relates to respiratory filtration masks that offer protection from hazardous particulate aerosols, vapors, and the like. Specifically, the invention addresses respiratory protection from biological warfare agents in a half-mask configuration.
2. Description of the Prior Art
Respiratory protection masks have been used by the military and police forces as protection against the inhalation of hazardous particulate matter, such as smoke and toxic gas. In the field of respiratory protection, one of the factors by which the level of protection provided by a mask is measured is its fit. The standard United States military mask achieves a fit providing adequate protection against biological as well as chemical warfare agents. However, these military masks seal around the periphery of the face and are referred to as "full face masks". Although such masks provide a high level of protection, they also burden the user to a significant degree. For example, vision is restricted and the use of sights and lenses is made difficult. In addition, full face masks create a heat and weight burden for the user and a feeling of enclosure.
Commercial versions of respiratory protection masks, used to protect the wearer from paint fumes, particulate, and other vapors, are "half masks" that seal around the wearer's nose and mouth. The fit of half masks is generally regarded as inadequate to meet the military standard for protection against biological agents. Commercial evacuation or escape masks utilize a snorkel type mouthpiece and a nose clamp to provide protection while the wearer leaves an area of hazardous vapors. Despite these developments in respiratory protection masks, there has been no protection made which meets the military standard for protection against biological agents in a half-mask form and provides for respiration through the nose as well as the mouth.
It would be desirable to provide a half-mask that meets the military standard for protection against biological agents without the disadvantages of a full face mask configuration. For that purpose, there is provided a respiratory protection half-mask which comprises a mouthpiece seal, constructed from a flexible plastic insert, in combination with high efficiency nose seals which are constructed from foam rubber and a high efficiency particulate filter medium for filtration of biological agents. It is also possible to add chemical vapor adsorbing medium to this mask to provide limited protection against chemical agents and other hazardous vapors.